The incidence of stroke or transient ischemic attack within 90 days was 13 cases, including 8 cases of CYP2C19 gene deletion, 5 cases of CYP2C19 gene carriers, 6 cases of vertebrobasilar artery extracranial stenosis, and 7 cases of vertebrobasilar artery intracranial stenosis. The gene discussed is CYP2C19; the disease is transient ischemic attack.